[PATCH] D41505: [DAG] Teach findBaseOffset to interpret indexes of indexed memory operations

[Nirav Dave via Phabricator via llvm-commits]

niravd updated this revision to Diff 128524.
niravd retitled this revision from "[DAG] Teach BaseIndexOffset to correctly deal with with indexed operations" to "[DAG] Teach findBaseOffset to interpret indexes of indexed memory operations".
niravd edited the summary of this revision.
niravd added a comment.

Factored out the indexed memory operation correctness check into D417101.


https://reviews.llvm.org/D41505

Files:
  llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
  llvm/test/CodeGen/AArch64/arm64-abi-varargs.ll
  llvm/test/CodeGen/AArch64/swifterror.ll


Index: llvm/test/CodeGen/AArch64/swifterror.ll
===================================================================
--- llvm/test/CodeGen/AArch64/swifterror.ll
+++ llvm/test/CodeGen/AArch64/swifterror.ll
@@ -316,12 +316,11 @@
 ; First vararg
 ; CHECK-APPLE-DAG: orr {{x[0-9]+}}, [[ARGS]], #0x8
 ; CHECK-APPLE-DAG: ldr {{w[0-9]+}}, [{{.*}}[[TMP]], #16]
-; CHECK-APPLE-DAG: add {{x[0-9]+}}, {{x[0-9]+}}, #8
 ; Second vararg
 ; CHECK-APPLE-DAG: ldr {{w[0-9]+}}, [{{x[0-9]+}}], #8
 ; CHECK-APPLE-DAG: add {{x[0-9]+}}, {{x[0-9]+}}, #16
 ; Third vararg
-; CHECK-APPLE: ldr {{w[0-9]+}}, [{{x[0-9]+}}]
+; CHECK-APPLE: ldr {{w[0-9]+}}, [{{x[0-9]+}}], #8
 
 ; CHECK-APPLE: mov x21, x0
 ; CHECK-APPLE-NOT: x21
Index: llvm/test/CodeGen/AArch64/arm64-abi-varargs.ll
===================================================================
--- llvm/test/CodeGen/AArch64/arm64-abi-varargs.ll
+++ llvm/test/CodeGen/AArch64/arm64-abi-varargs.ll
@@ -13,9 +13,8 @@
 ; CHECK: ldr {{w[0-9]+}}, [sp, #72]
 ; Second vararg
 ; CHECK: ldr {{w[0-9]+}}, [{{x[0-9]+}}], #8
-; CHECK: add {{x[0-9]+}}, {{x[0-9]+}}, #8
 ; Third vararg
-; CHECK: ldr {{w[0-9]+}}, [{{x[0-9]+}}]
+; CHECK: ldr {{w[0-9]+}}, [{{x[0-9]+}}], #8
   %1 = alloca i32, align 4
   %2 = alloca i32, align 4
   %3 = alloca i32, align 4
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
@@ -96,16 +96,43 @@
   }
 
   // Consume constant adds & ors with appropriate masking.
-  while (Base->getOpcode() == ISD::ADD || Base->getOpcode() == ISD::OR) {
-    if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1))) {
+  while (true) {
+    switch (Base->getOpcode()) {
+    case ISD::OR:
       // Only consider ORs which act as adds.
-      if (Base->getOpcode() == ISD::OR &&
-          !DAG.MaskedValueIsZero(Base->getOperand(0), C->getAPIntValue()))
-        break;
-      Offset += C->getSExtValue();
-      Base = Base->getOperand(0);
-      continue;
+      if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1)))
+        if (DAG.MaskedValueIsZero(Base->getOperand(0), C->getAPIntValue())) {
+          Offset += C->getSExtValue();
+          Base = Base->getOperand(0);
+          continue;
+        }
+      break;
+    case ISD::ADD:
+      if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1))) {
+        Offset += C->getSExtValue();
+        Base = Base->getOperand(0);
+        continue;
+      }
+      break;
+    case ISD::LOAD:
+    case ISD::STORE: {
+      auto *LSBase = cast<LSBaseSDNode>(Base.getNode());
+      if (LSBase->isIndexed() &&
+          Base.getResNo() == (LSBase->getNumValues() - 2))
+        if (auto *C = dyn_cast<ConstantSDNode>(LSBase->getOffset())) {
+          auto Off = C->getSExtValue();
+          if (LSBase->getAddressingMode() == ISD::PRE_DEC ||
+              LSBase->getAddressingMode() == ISD::POST_DEC)
+            Offset -= Off;
+          else
+            Offset += Off;
+          Base = LSBase->getBasePtr();
+          continue;
+        }
+      break;
+    }
     }
+    // If we get here break out of the loop.
     break;
   }
 


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